如何在c中间接设置struct的值？

struct Person {
    char name[20];
    int age;
};

struct Person p;
p.age = 25;
strcpy(p.name, "John");

struct Person {
    char name[20];
    int age;
};

struct Person p = {"John", 25};

struct Person {
    char name[20];
    int age;
};

struct Person p;
struct Person *ptr = &p;
ptr->age = 25;
strcpy(ptr->name, "John");

struct Person {
    char name[20];
    int age;
};

void setPerson(struct Person *p, char *name, int age) {
    strcpy(p->name, name);
    p->age = age;
}

struct Person p;
setPerson(&p, "John", 25);